1.灰度图像映射
vtkImageLuminance负责将一个RGB彩色图像转换为一个单组分的灰度图像。映射公式如下：
luminance = 0.3*R + 0.59*G + 0.11*B
该公式中，R为输入图像的第一分量（红色），G为第二分量（绿色），B为第三分量（蓝色）。这个计算结果计算一个RGB颜色的亮度。该类的使用也比较简单，用户无须设置参数，代码如下： 
 1 #include <vtkAutoInit.h>
 2 VTK_MODULE_INIT(vtkRenderingOpenGL);
 3  
 4 #include <vtkSmartPointer.h>
 5 #include <vtkBMPReader.h>
 6 #include <vtkImageLuminance.h>
 7 #include <vtkImageActor.h>
 8 #include <vtkRenderer.h>
 9 #include <vtkRenderWindow.h>
10 #include <vtkRenderWindowInteractor.h>
11 #include <vtkInteractorStyleImage.h>
12  
13 int main()
14 {
15     vtkSmartPointer<vtkBMPReader> reader =
16         vtkSmartPointer<vtkBMPReader>::New();
17     reader->SetFileName("lena.bmp");
18  
19     vtkSmartPointer<vtkImageLuminance> luminanceFilter =
20         vtkSmartPointer<vtkImageLuminance>::New();
21     luminanceFilter->SetInputConnection(reader->GetOutputPort());
22     luminanceFilter->Update();
23     //原始演员
24     vtkSmartPointer<vtkImageActor> origActor =
25         vtkSmartPointer<vtkImageActor>::New();
26     origActor->SetInputData(reader->GetOutput());
27     //灰度演员
28     vtkSmartPointer<vtkImageActor> shiftscaleActor =
29         vtkSmartPointer<vtkImageActor>::New();
30     shiftscaleActor->SetInputData(luminanceFilter->GetOutput());
31     double origView[4] = { 0.0, 0.0, 0.5, 1.0 };
32     double shiftscaleView[4] = { 0.5, 0.0, 1.0, 1.0 };
33     //原始演员化妆
34     vtkSmartPointer<vtkRenderer> origRender =
35         vtkSmartPointer<vtkRenderer>::New();
36     origRender->SetViewport(origView);
37     origRender->AddActor(origActor);
38     origRender->ResetCamera();
39     origRender->SetBackground(1.0, 1.0, 1.0);
40     //灰度演员化妆
41     vtkSmartPointer<vtkRenderer> shiftscaleRender =
42         vtkSmartPointer<vtkRenderer>::New();
43     shiftscaleRender->SetViewport(shiftscaleView);
44     shiftscaleRender->AddActor(shiftscaleActor);
45     shiftscaleRender->ResetCamera();
46     shiftscaleRender->SetBackground(1.0, 1.0, 1.0);
47  
48     vtkSmartPointer<vtkRenderWindow> renderwindow =
49         vtkSmartPointer<vtkRenderWindow>::New();
50     renderwindow->AddRenderer(origRender);
51     renderwindow->AddRenderer(shiftscaleRender);
52     renderwindow->SetSize(720, 480);
53     renderwindow->Render();
54     renderwindow->SetWindowName("RGB to Gray");
55  
56     vtkSmartPointer<vtkRenderWindowInteractor> rwi =
57         vtkSmartPointer<vtkRenderWindowInteractor>::New();
58     vtkSmartPointer<vtkInteractorStyleImage> style =
59         vtkSmartPointer<vtkInteractorStyleImage>::New();
60     rwi->SetInteractorStyle(style);
61     rwi->SetRenderWindow(renderwindow);
62     rwi->Initialize();
63  
64     rwi->Start();
65     return 0;
66 }

VTK 图像基本操作_彩色图像生成灰度图像_灰度